I have tried many spam control software and recently found POP file, installed it and tried it out. Briefly, the POP File is:-
POPFile is an automatic mail classification tool. Once properly set up and trained, it will scan all email as it arrives and classify it based on your training. You can give it a simple job, like separating out junk e-mail, or a complicated one—like filing mail into a dozen folders. Think of it as a personal assistant for your inbox.
Installation and configuration is easy and the profile server basically like a proxy and process all incoming mail, classify it. Substantial reclassification is needed initially to train the POP File and after about a period of 2 weeks, you will notice that the accuracy is well above 98%.
I have tried POP File on two mail boxes, one with small email volume ( 100 mails a day) and one with substantial volume (about 1000 mails a day). Working on first box is easy but working with the later mail box require substantial work to perform reclassification within the first two weeks. POP File is now at version v0.22.3 and more are to come in the future. POP File is free to download and use and you many want to donate if you find the software is good.